Journal Article

Anatomical and transcriptional dynamics of maize embryonic leaves during seed germination

Chen, Di-Rong, Chang, Yao-Ming, Liu, Wen-Yu, Li, Wen-Hsiung, Wu, Yeh-Hwa, Huang, Hsuan-Cheng, Shih, Arthur Chun-Chieh, Ku, Maurice Sun-Ben, Lin, Hsin-Hung, Lu, Mei-Yeh Jade, Lu, Chen-Hua, Shiu, Shin-Han, Chen, Sean Chun-Chang, Sheue, Chiou-Rong, Yu, Chun-Ping

2013

Overview

Our anatomical analysis revealed that a dry maize seed contains four to five embryonic leaves at different developmental stages. Rudimentary kranz structure (KS) is apparent in the first leaf with a substantial density, but its density decreases toward younger leaves. Upon imbibition, leaf expansion occurs rapidly with new KSs initiated from the palisade-like ground meristem cells in the middle of the leaf. In parallel to the anatomical analysis, we obtained the time course transcriptomes for the embryonic leaves in dry and imbibed seeds every 6 h up to hour 72. Over this time course, the embryonic leaves exhibit transcripts of 30,255 genes at a level that can be regarded as “expressed.” In dry seeds, ∼25,500 genes are expressed, showing functional enrichment in transcription, RNA processing, protein synthesis, primary metabolic pathways, and calcium transport. During the 72-h time course, ∼13,900 genes, including 590 transcription factor genes, are differentially expressed. Indeed, by 30 h postimbibition, ∼2,200 genes expressed in dry seeds are already down-regulated, and ∼2,000 are up-regulated. Moreover, the top 1% expressed genes at 54 h or later are very different from those before 30 h, reflecting important developmental and physiological transitions. Interestingly, clusters of genes involved in hormone metabolism, signaling, and responses are differentially expressed at various time points and TF gene expression is also modular and stage specific. Our dataset provides an opportunity for hypothesizing the timing of regulatory actions, particularly in the context of KS development.

• Publisher: National Academy of Sciences
• Subject: biochemical pathways / Biological Sciences / calcium / Cellular differentiation / Corn / data collection / Datasets / Developmental biology / Developmental stages / Epidermal cells / Gene expression / Gene Expression Profiling / Gene expression regulation / Gene Expression Regulation, Developmental / Gene Expression Regulation, Plant / Genes / Genes, Plant / Genetics / Germination / Germination - genetics / hormone metabolism / imbibition / Leaf development / Leaves / meristems / Mesophyll cells / Plant Growth Regulators - genetics / Plant Leaves - embryology / Plant Leaves - genetics / Plant Proteins - genetics / Protein synthesis / Ribonucleic acid / RNA / RNA, Plant - genetics / Seed germination / Seeds / Seeds - embryology / Seeds - genetics / Stem cells / transcription (genetics) / transcription factors / Transcription Factors - genetics / transcriptome / Zea mays - embryology / Zea mays - genetics / Zea mays - physiology